The purpose of this study is to establish a random clone library of Drosophila melanogaster which are mapped on the salivary gland chromosome and construct a data bank system based on them. we isolated about 800 clones randomly from the lambda phage genomic library of Drosophila melanogaster and constructed a phage stock library and extracted DNA samples from each clone. We mapped these clones on the salivary gland chromosome by in situ hybridization technique. Up to date, 286 clones are mapped and the rest of them are now under progress. 190 clones are mapped on the single sites on the chromosomes and the rest of 96 (33.6%) are mapped on the multiple locations. These clones are considered to contain repetitive sequences or the movable genetic elements. Among these clones which were mapped on the single sites, 31 were mapped on the X, 40 were mapped on the 2L, 55 were mapped on the 2R, 35 were mapped on the 3L and 37 were mapped on the 3R. This result indicates that clones were chosen randomly from the genome. Assuming the Poisson distribution the mean frequency of clones having a repetitive sequence is estimated to be 0.409.On the other hand, we collected DNA clones of Drosophila melanogaster which have been mapped on the salivary gland chromosomes from the laboratories of all over the world. We so far obtained about 50 clones. Further more we are to get P1 phage library clones from Dr. G. Rubin of Univ. of California. After we establish the clone bank of these collections, we will start service for distribute these clones on request.